Beihang University China Key points The toroidal fields are produced in the bulk of the convection zone by the latitudinal shear The tachocline is unimportant in our model Zebin Zhang amp ID: 1025502
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1. A Babcock-Leighton type solar dynamo working in the bulk of the convection zoneBeihang University, ChinaKey points The toroidal fields are produced in the bulk of the convection zone by the latitudinal shearThe tachocline is unimportant in our model Zebin Zhang & Jie Jiang
2. How is the toroidal field produced Source term of the toroidal field in dynamo equations: Differential rotationRadial shearLatitudinal shearIn the tachocline and near surface shear layerIn the bulk of the convection zoneOriginal Babcock’s scenarioeffectLatitudinal shearPopular opinion Babcock (1960)The toroidal field is produced in the tachocline by the radial shear. E.g., flux transport dyanmo (FTD) model.? Scenario of FTD effectThin flux tube simulations (for reviews, see Fan 2009) supported by
3. Nelson et al.(2013)Nelson et al. (2013): Rope-like structures of magnetic flux could be produced in the bulk of the convection zone Fullly convective stars have the same rotation-activity relationship with the partially convective stars.Dynamo may not operate in the tachoclineWright & Drake(2016)?If the tachocline is importantSuch relationship should not existIn the tachocline by the radial shear ?In the bulk of the convection zone by the latitudinal shearThe latitudinal shear is the dominant generator of net toroidal flux (Cameron & Schüssler 2015)How is the toroidal field produced
4. Aims of our workDeveloping a Babcock-Leighton type solar dynamo working in the bulk of the convection zoneGlobal dipolar poloidal fields are stretched by the latitudinal shear to produce the toroidal fields in the bulk of the convection zoneBabcock (1960)Objective Regeneration process of the toroidal field is consistent with original Babcock’s scenario Global dipolar poloidal fields latitudinal shearToroidal fields
5. ModelDynamo equations:Differential rotation and meridional circulationTurbulent diffusivityBL-type source termNear-surface pumpingVertical outer boundary conditionBL-type dynamo modelSurface flux transport modelCameron et al. (2012)consistent(More details in Zebin Zhang, and Jie Jiang, A Babcock-Leighton type solar dynamo working in the bulk of the convection zone, to be submitted)
6. Reference solutionAB K, Harvey (2000)ephemeral regionsactive regions
7. Purely radial fields at the surface, Bθ≈0. (consistent with SFT simulations) Purely latitudinal fields in the bulk of the convection zone, Br≈0.The toroidal fields are generated in the bulk of the convection zone by the latitudinal shearEvolution of the poloidal and toroidal fieldsLatitudinal shear works on the global dipoleSimple configuration of the poloidal fieldSource term of B:
8. Dikpati et al.(1999)Chatterjee et al.(2004)Comparison with previous representative models
9. ConclusionWe develop a new BL-type dynamo model which is independent of the tachoclineThe poloidal field has a simple dipolar configuration. Latitudinal shear works on the global dipole to produce the toroidal fields in the bulk of the convection zone.